A duct type air conditioning system according to the related art, a representative example of which is described in Patent Literature 1, includes an outdoor unit included in an air conditioner; an indoor unit included in the air conditioner; room temperature sensors; a duct that is connected to the outlet of the indoor unit; a plurality of duct-branch portions that are branching from the duct and disposed in a plurality of air-conditioned spaces; a plurality of dampers that are disposed in the duct-branch portions to open and close air channels in the duct-branch portions; and a plurality of outlets that are disposed at the ends of the duct-branch portions to discharge conditioned air to the air-conditioned spaces. In the duct type air conditioning system according to the related art, air-conditioning of the air-conditioned spaces is performed by opening and closing the dampers.